Tapping attachment for lathes



Feb. 4, 1930. o. HEGSTAD 6,0

TAPPING ATTACHMENT FOR LATHES 1 Filed Sept. 2?, 192a :s Sheets-Sheet 2 Feb. 4, 1930.

0. HEGSTAD TAPPING ATTACHMENT FOR LATHES Filed Sept. 27, 1926.

3 Sheets-Sheet 3 l nxfenta; waf 52 85 Patented Feb. 4,

were, STATES PATNT 7 OLAF HEGSTAD, or" cn oneo, rumors, .assrenon TO riiooun MANUFACTURING 00.,

" ACOBIE'ORATION or inninois I v TArrINe nrrnoi-iivinmi non LA'rHEs Application filed September 27,1926. Serial No. 138,092 p Jlheinvention relates to improvements in "tapping attachments for lathes, and'particularly to tapping attachments adapted for'attachment to lathes in which the work is positively rotated, during the tapping operation, and the tap held in such attachment against rotation and gradually advanced into the bore of the .work to cutthe screw threads therein, v V v In lathes of known construction it is usu ally necessary to stop'the lathe and to rotate the work in a direction opposite: tothe prewviousdirection of rotation for the purpose of withdrawing the-tap after it has cut the threads to. the desired depth, whereby the tap is gradually unscrewed fi'rom the threaded v opening thus produced. I 7

'It is an object of thepresent invention to avoid thenecessity of stopping the work, or rotating the same-in a direction opposite to the direction in which it is rotated during 7 the tapping o eration, and to effect the easy withdrawal oi the tap by imparting to. the tap a rotary movement relatively to the work, and in such direction, that the tap will be unscrewed automatically from the threaded bore.

It isalso an object of the invention to provide-a lathe attaohmentin which, during the tapping operation, that the tap is'positively locked against rotation, but during the tap releasing operation that the tap is rotated at ahigherrate of speed without changing the direction of rotation of the work, thereby producing the unscrewing operation of the tap and at the same time axially withdrawing it frointhe work... I v has the object "of :providing a tapping attachment for lathes,'in .40 which the operationof withdrawing the tap tromthe threaded bore is started automatically after the tap has advanced to a selectively predetermined depth. into the bore to The threaded. t The invention also has the object of pro;-

h nvent n a o ducing a .relativej'rotary m ovem'ent between the tap and work, forthe purpose of effecting thewithdrawal of the tap without necessitating the interruptionof, or the changing. ,50 ofthe direction of rotating of the work, and.

rotated. 1

' line 9- 9,of Fig. 7:

tappet for the attachment, and J to accomplish this rotationof thetap from. the drive through which the work is' being Another object of the invention is to provide a tapping attachment for lathes, particularly for turret lathes, in. which, subsequent to the automatic withdrawal of the tap from the finished bore, eflected without interrupting the rotation of the work, the

mechanism controlling this withdrawal, is automatically placed into readiness' for the next operation through the. rotation of.

turret. V

, With these and'numerousother objects in view, an embodiment of the invention is described by wayof example only in the following specification, and is illustrated in the accompanying drawings," but it p is only ,intended to be limited by the scope of the claims and the spirit of the real invention disclosed.

I In the drawings: i Fig. 1 is a top plan view of'a portion of the turret lathe showing the invention, the

turret being advanced towards the work;

Fig. 2 is a similar top planpview with the r turret in position withdrawn from the work; Fig. 3 is a longitudinal sectional view shown with certain parts in elevation to illustrate the reverse actuatingmechanism;

Fig. 4 is a sectionalviewof gearing on line 44: of Fig. 35 I 'Fig. 5 is a fragmentary perspective view of a clutch'carrying spindle; I Fig. 6 is a perspective view of a movable clutch member forsaid spindle V V Fig. 7 is anend elevation, partly in section, V

of the turret attachment; p I

, Fig. 8 is aside elevation ofisa'icl attachment; i

"Fig. 9. shows on a'larger-scale a'section on Fig. 10 is a detail sectional view line i 10-1Q"ofFig.9;. U

Fig. 11 shows perspectively a'key actuating Fig. 12 shows perspectivel' the movable key or abutment element for the gearing.

In Figs 1 and 2, only the principalportions of theturret lathe parts-that are relevant to the v resent invention are illustrated. .The'

bed 1 of the lathe supports at one end a suit able hearing or head stock 2 for a shaft 3 (Fig. 3) which may be driven by the pulley 4. This shaft is associated with a chuck 5 in which the work 6 is held so as to be rotated together with the chuck. A turret 7, shown here to be of polygonal outline and adapted to support in a known way the various tools 8, 8 8 etc., is adapted to movement in a rectilinear path towards and away from the chuck by mechanism which is not fully illus trated in the drawings, but which maybe of any conventional form, such as is generally used on lathes of this type. The hand wheel 9 may serve for manually actuating the turret turret 7 to which the tap is to be secured,

there is operatively associated with the turret, as for instance bymeans ofthe chuck 11, a nonrotatable or stationary stem on shaft 12 whichserves as a mountin for the tapping attachment.

The attachment comprises a casing which consists in the embodiment illustrated of two portions or casings 13 and 14 securely held to each other'by bolts or countersunkfilister head cap screws 15 andmaintained in proper aligned position by dowel pins 16 or in any other-appropriate way. The rear portion or section 13 of said casing is fixedly secured to the stationary shaft or stem 12, and the lower part of the front portion of the casing receives rotatably therein a gear wheel 17 having an extended hub 18 which is carried by the bearing extension 19 of the casing portion 'or part 14. Removably secured within the hub extension 18 of the gear 17a chuck or sleeve 20 is mounted adapted to receive the tapping tool 21. This chuck 20 is fixedly held in the hub 18 by headless set screws 22. The casing formed of the two parts 13 and 14 receives in its upper portion a spindle 23 on which is loosely or rotatably mounted a bearing sleeve 2e, this bearing sleeve being provided with a flange 25 through which one or more dowel pins 26 project axially, to maintain-in-fixed connection with the bearing sleeve 24; a ring gear 27 preferably having the same diameter as the gear 17 in the lower portion of the casing, or the gear may be made integral with said sleeve,.the two gears being arranged to mesh with each other as indicated in. Fig; 4 of the drawings.

7 received.

The bed 1 of the lathe also carries a transverse support 28 to which a tool post or the like, not shown in the drawing, may be seecured, for the purpose of finishing the work held in the chuck 5. In the embodiment illustrated a transverse bar 29 is mounted on the support 28, and a stop 30 in the form of an angle bar is removably secured to the bar 29 by means of the screws 31-. It is obviousthat the support 28 may be adjusted longitudinally as well as transversely of the lathe in the ordinary way, and that on this support 28 the stop carrier 29 may also be adjusted axially cated at 34, and'has intermediate the pivot and its end an opening 35 through which the stem 36 of a movable key 37 projects, said key being slidably mounted in a key way 38 on the stationary shaft 12, which serves in place of the ordinary turret tool holder.

In the normal position of said key 37 which is the position for tappingthe work, one end of the key projects against and in engagement with one of a plurality of clutch teeth 39 which are formed on the rear face of the gear 17, thereby maintaining said gear against rotation on the stem, and as the gear is fixedly associated with the tapping tool 21 by the screws 22, as shown in Fig. 3, it is obvious that the locking key 37 will normally prevent the rotation of said gear 17, and will thereby also fixedly hold the tapping tool'21 against rotation. Owing to the rotation of the work 6 and the rectilinear advance of the tap into'the bore 6 of the work 6, the tapping operation will be carried out.

The ofiset extremity 40 of the arm 34 is provided with anopening in which the pin-4L0 is This pin is mounted on the head ll of a dog 4-2 movably secured to the casing sections 13, 14, as indicated in Fig. 4. The

casing is equipped for thispurpose with a guide plate 43 grooved to receive slidably the dog 42 and secured to thecasing by means of suitable screws 44; The hook 45 at the other end of the dog 42 is adapted for cooperation with the stop 30, and upon engagement of the hook with said stop30 during theadvance of the tool into the work, they dog42 will be displaced relatively to the casing,' thereby causing the lever 32 to be rockedabout its pivot 33. V

Theopposite arm 46' of-the lever 32 carries at its free end'a lug 47'inmovahl'e engagei merit-with a clutch member48' which is 'spli-ned to the spindle 23 andfwhich'upon oscillation of the lever '32 in aj'predet'ermined direction ma be advanced on said spindle towards the left tFigj) tomove the clutch teeth 49 on said sIeeveAS-intoengagement with 'correspending clutchteeth 50 on the hub member hub extension 55 f a gear bearlng casing 57 which 24ewhich is rot-atably supported in the casing sectiOnslS and l l on the spindle 23. The spindle 23 extending rotatably through said *h'nbLmeniber 24jis surrounded by a spring 51 which is' inte'rposed between the front face of the hub-member 24: and a-clutch head52 securely fastenednear the front of the spindle. This clutch head 1' terminates in a face provided withcl-utch teeth '53 adapted for cooperationwith suitable clutch teeth Mon a 56 mounted in a is secured to the frame, of the machine. The gear 56' is of smallerdiameternthan and is in. permanent mesh with a gear'58 which is operatively. as-

' sociatedi'with thechuok in: any suitable Iwayand; therefore, during I the operation of the machineiit isno-rmally rotated'at a greater fsp eedlthanthatat which the'cliuck 5 is rotated'pr'eferably a ratio ofl to 2.

plunger 59 is'normallyforced w projectgoutward by, the spring 60' and isbeveled in. op-

posite directions, as indicated in EigaIO. A

f pin 61 adapted for cooperationwith'the .bevt eledefac e s of the plunger '59is secured to the lever 32iwhereby upon the forcible oscillation: of'said lever'f-rom one side of. the stop pin 59 to stlie other side the accidentalreturn oscillation of the lever is prevented," 5 [:The operation of the device maybe describedfas-follows V Tjhe attachment co'mprlsing the casing secpressed. The hub f tions 13' and 14 with the gearing contained therein is {securedto th'eshaft or stem 12 of thetu'r'ret 7, in the place provided for. holding a'tool. This attachment contains the tap- -2-1 which remains stationarywhile the .work

6 is being rotated b-ythepulleyA'and-the chuck 5'. Duririgthe advance'of the turret g-7gtow-ard the work, the attachment is thereby fed toward thehead'stock f the lathe and owing to this-advancethetap cuts the thread in the bore of the rotating workpiece 6. The spindle-:23 with its rounded end gradually en- .tfers the "socket of thehubextension 55 of the dle 23; whileat the same time, owing to the axial advance of the attachment relatively to theg'head stock 2,- the spring 51' will be comspindli" 28 will be against rotation bythe key 37. 1

' the depending hook speed.

clutch teeth 53- with the clutch teeth; of the extension rotation may be imparted to the spinmember 2ftloose on the; held against; rotation, as this hat-f mem er is fixe tio he g a 2 Which is in engagement with the gear iof'eq ual diameter, the last named gear bein'g locke'd After-the turret attachmentha's sufiiciently thedesi'red depth, the dog 42 by meansiof engages th'estop :30, thereby initiating a displacement of said dog relatively to the casing and causing the lever 32 to swing over, overcoming the spring actu1- v ated' stop plunger 59-. Thisrocking move;

ment' of the lever rapidly withdrawsthe looking key 37 out of its locking lposition relatively I to the teeth 39* of the gear 17,"'so that rotation of said gear" may now 'f're'e'ly take place.

' At the same time the opposite arm l6 of I lever 32 moves the clutch sleeve 48falong i ts feather way t ooperative "position with respect tothe teeth-'50ofthe'hub member 24:, and since the clutch sleeve is rotated by the spindle 23 at twice the rate of speed of the chuck thisdri'vewill now be imparted to the gear 27 and from said gear to the gear 17, whereby the tap 21 is rotated in thesame direction, as the-work but'at ahigher rate of a A relative r with respect to thework takes place'in a direction whereby the tap is automatically un screwedlfrom the tapped opening just produced in the work."

advanced to effect the tappingoperation totation; therefore, of theta- This withdrawal or the tap fromtthe' fin- I ish'ed bore maybe aidedby the withdrawal of the slide inwhich the turret is mounted'in a direction away- 'from the work although this is not usuallynecessary. "During this :movement of the slide,for"instance from the position illustrated in Fig. I'to the position 1 shown in 'Fig. 2, the entire attachment come prisln the casing sections 13'and l4 and the elements carried thereby will al'sobe withdrawn. Owing to the ithdraw'al'of the enattachment away fromifthe'lwork,the spring '51- surrounding "the front portion of r the counters'h aft 23 will exert "a pressure be tween me bers 52 and 24 thereby keeping 'lutch;teeth' 5'3' and 54' in operative engagement.

i a The dog 42 vvhich' has been-moved one endjpo'sition owing to its engagement with the 'stop:30"wi1 1 rema n-this" e d. P sition, so that the key 37 normally"locking the gear 17' associated with 'thetap-is 'releasedfand the free to. rotatef since? the counterear'56 and owingitothe engagement of the aft 3 b t of teh r tio tj WithgthG fore, lthey will ,reinain stationary, 1

1 lThe lever; 32mhavmg 50 or the h ub member 24', will remaininihis "p s-a a; 2,..Simg ae s le ato thislgear 1,7. or. the tap 21, there ingstop' 59 prevent'sthereturn rocking moveofsaid lever.

1 tion shown inFig l', anoperation-whichwill also induce the lever 32 to rock on its pivot 33 against thetension. ofthe yielding stop 59. The parts'ares then all in-readiness for the. next withdrawal operation. of the tap,

:and; upon:approachofrthea to the work,

theoperation can again'be performed.

Iiclaim: 1'. Astappingattachment for lathes having a, drive; shaft for'theworkand a support for a-tap,.saicl support being movable axially of the work, including" a countershaf-t driven from said drive shaft, a tram of transmission gears between said :countershaft and the tap,

and key means .on thesupport of the tap for engaging :in1andp.os-itively lockingone of the gears said train of transmission gears against rotation during-the; tapping operation 2A tapping attachment. for lathes having z-a drivIe-shaftforthe-Work and a-support for thztfifPrIIlOWfiEblG axially of the work, including aicountenshaft driven from said drive shaft, a gear loose on said countershaft, a gear-"in fi x'ed relation toath'e-tap,. and means onrthesupport for positively connecting said v first namedagea'r Wlt hiSfliCl oountershaft, said first -3.;Hd::SCOHd gear being: in engagement 3. A tapping:attachment for lathes having a drive shaft for .thework and asupport for thetap mowableaxially :of the work, acountershaftdriven from said drive shaft, a" gear loosely mounted on said countershaft, asec- 0nd gear in engagement therewith and fixedly connected-to the-tap, means-on the support for" automaticallylocking one. of said gears against rotation, and means. on the: support I forpera tively connecting; said: first named gear withlsaidcountershaft. V

$1.. A tappingattachment forlatheshaming aadhlateShaft. for theworkand asupport for the tap movable axially of the work,lincluding a \countershaft' driven from said, drive shaft, a gear loosely mounted' on said countershaft, a gear fixedly associated. with the tap, means on .ithe-snpp orjt for. normally locking second-T gear" against rotation, and

meansfor releasing look: from" said v-secend en; operatively connecting "misstatements the countersha-ft'.

92 A} tapping-attachment forilathes of the 5.1- A tappingattachment for lathes having a drive shaft .for the work and asupport for the tap axially movable of the work, a countershaft adapted to be driven from the drive shaft, a gear loosely associated with said countershaft, asecond gear in mesh with said first named gear and fixedly associated with the tap, means on the supportvfor normally locking said second gear against rotation, and means on the support for simultaneously unlocking said second gear and for operatively connecting the first named gear with said countershaft.

6; A tapping attachment for latheshaving axlriveshaft for the work and'asupport for thetapaxially movable of the work, a stop on the lathe adapted to limit the axial movement of the support in direction towards the work, a secondary shaft adapted to be driven from; said, drive shaft, a gear loosely associated with saidrsecond shaft, a second gear in engagement "with said first named gear and fixedly associated with the tap,'and means on the support operable upon engagement with saidstop on the lathefor rapidly establishing operative connection between said first named gearsand said second vshaft to impart rotary ;movement to the tap.

7. A tapping attachment 'for'lathes having a driveshaft for thework and a support for the tapaxially movable of the work, including apair of gears, one fixedly associated with the drive shaft and the other one permanently. driven by said first gear, aIcountershaft loosely carried by the support and axially slidabletherein, a releasable clutch connection between said second gear and said countershaft, a third gear loosely mounted on said countershaft and carriedby the support ofthe' tap, a' fourth gear fixedly associated with the tap and in mesh with said third gear, and means for efl'ecting a fixed connection between said third gear and the cou-ntershaft' subsequent to the establishment of the clutch connection between the countershaft and thesecond named gear, said means being operable automatically upon the 'sup portfhavingbeen advanced to a predeterminedpoint in its-advance towards the work.

ing a drive shaft for the work and a support for the tap movableaxially of the work, comprising a pair of gears-one of which is fixedly associated with the drive shaft while the otherone-is in mesh with said first named gear, a countershaft loosely rotatable in the support, a gear in the scupport rotatable-on said countershaft, another gear in the support in mesh with the third named gear and fixedly-associated with the" tap, and means for successively establishing a clutch connection between said countershaft and said sec- 0nd gear, and between said 8. A tapping attachment'for' lathes-havthird gear and V typein which the work is-associated'with a type in which a drive shaft permanently rotates the work while a support for the tap is movable axially of the work, comprising a largergearpermanently associated with the drive shaft, a smaller gear'in engagement with said first named gear and driven there; by, a 'countersh'aift loosely rotatable in; the support and slidable' therein, a Fall" ofg'ears' in said support in mesh witheach other, one ofsaid gears beingloosely associated with said countershaft and the other one being fixedly ass-ociatedwit'h-the tap, means for normally locking said last named gear against rotation during the advance of th'e'support in directiontowards the work,a clut'chbe towards the vwork, the means for rendering" the secondnamed-clutch opeartive being.actu'-' ate-d automatically, upon the supportfar'riving at aipredetermined point in its path dun mg the advance towardsthe work? 1 0; A tapping. atta h ent. tor lathes' having a drive'shaft for the work and a support for; thertap movable axially of the work, a

train of transmission ge arsjbetlween said drive. shaft and the. tap ,and means on the support for normally lockingone of. the gears gof the train against rotation, andfcommon' means on thesupport for automaticallyetfecting'release ofsaid locking meansrand for establishing driving connection between" said drive "gear of the work and another gear of said train. 11, A tapping attachment forlathes ofthe drive shaft permanently rotated, and a support for'the tap is ',movable axially ofthe work, comprisingj a stop adjustably mounted on the lathe-, a casingiformmg part of; said supportoando containing 1 a pairfof gears, a

countershaft looselyassociate'd with one ofsaid gears, a clutch lever mounted on said casing, a sliding element flexibly associated with said clutch lever and adapted to engage the stop upon advance of the support in direction towards the work, aclutch under con-- trol of saidlever on the countershaft loosely mounted in said support and loosely associated with one of the gears in said support, a locking element for the other gear in said 7 support, said locking element being operatively connected with said lever, whereby upon engagement ofsaid sliding element with said support said lever is imparted a rocking movement to move the clutch on the countershaft to operative position and to move the locking 'elementin the support to inopera-' tive osition. V v

12. A tapping attachment for lathes having a drive shaft permanently associated with the work and a support for the tap movable axially of the work, a gearin said sup- 1 port fixedly associated with the tap, a locking element for said gear, a 'countershaft loosely mounted in said support, another gear I loosely related to said countershaft for said support and in engagement,'with said first named gear, a stop on the lathe, aslidable element carried by said support 7 and adapted for cooperation with said stop, a clutch'lever flexibly associated with said 'slida-ble-element and pivotally carried on the support, a clutch on the countershaft permanently engaged by said. lever, a: locking member 'for saidsfirst named gea'r within the support and connected with said lever,"whereby upon displace ment of said slidable element by said stop said lever is rocked to move theclutch to operative position relatively to said loose gear, andsaid lockingelement iswithdrawn from engagement with sald tap gear, means for retaming said lever in either of 1ts terminal posltions and a'clutch on said countershaft for o'perav v :13. A ppi g able turret on which the support forthe tap is mounted, a train of gears between said] 7 drlve shaft and the tap, means for normally locking one of said gears in the train otgears against rotation, means for automatically establishing driving relation throughout said train of gears, and means operative upo-nrotation of the turret vfrom tapping position to another operative position for reestablishoperation for saidfgear in the ing thello'cking train of gears.

ing a drive shat-tier permanently rotating the work, and a turret axially vand rotatably movableoir' thework, a train'of gears interposed between the drive shaft and the-tap,

means for rendering normally one of the gears ofthe train inoperative, a stop on -the lathe, and means controlled by the advance of the turret'in adirection towards'the work for establishing driving relation of said gear to other gearsiofthe train, andimeans opera tive upon rotation of the turret for interrupting automatically the driving relationof,

said gear. v g p 15. Altappin'gattachm'enet for lathes,-in

drive shalt and in which the'tap is carried v attachment for lathes havmg a drive shaft for the Work. and a rotatwhich the work is permanently driven by a loo '14;A'tappingattaohment for lathes i the lathecomprisingatrain'jof gears inte'r posed betweenthe drivershaft and the tap, means for normally render ng one Oll Bald gears inoperative as to driving relation to other gears, nie ans for normally locking an; I 7

other one ofsaid gearspositively against ro-,

-tation,.! means operative automatically upon advance of the 'turretfto' a predetermined point for automatically establishing the driving relation of said first named gear and for withdrawing the lock from said second named gear, and means operative upon rotation of said turret from a predetermined mounted on the turret and rotatably supporting two intermeshing gears, one of which supports the tap, a driving gear rotatable with the work, a second gear in permanent driven engagement with said last named gear, a shaft loosely extending rotatably and slidably through one of the gears in the casing carried by the turret, a clutch member fixedly 'mounted on said lastnamed shaft, one of the gears operable with the'work having a companion clutch member, a second clutch member mounted on said shaft supported'in the gear casing to be rotatable therewith and slidable thereon, a companion clutch member on one of the gears insaid casing, and means supported on said casing for operatively connecting said second clutchmember on the shaft with the companion clutch member on the gear subsequently to the engagement of the firstmentioned clutch members, and said clutch operatingmeans being dependent upon the movement of the gear casing relatively to a fixed point on the lathe.

17. A tapping attachment for lathes in which the work is permanently drivenby a shaft having a gear associated therewith to rotate with the speed of the work and in which the tap is supported by a turret axially movable of the work, including a fixed stem projecting from the turret, a gear casing fixedly mounted on said stem and, containing 18. A tapping attachment for lathes, in

which the work is permanently driven by a shaft operating a gear at the same speed as the work, a turret rotatable on the lathe and axially'movable of'the shaft, a gear casing fixed to said turret and containing two intermeshing gears, one of which is fixedly connected with the tap while the other one loosely supports for slidable and rotational movement a countershaft, means in the casing for positively locking said gears, means on the outside of the casing for exerting a driving force upon the countershaft, additional means outside the casing for establishing driving connection between the countershaft and the gear in the casing, through which said counte'rshaft extends, means for releasing the lock of the gears upon arrivalo'fthe turret at a predetermined point in it's p'ath of axial movement, and means for ree'stablishing' said locking connection for the. gears upon arrival of saidturre't at a predetermined-'point' in its path of rotational movement.

19. A tapping attachment for ilathes, in

which the work is permanentl driven by 'a shaft, and in which thetap isca'rrie'd by a turret, including a casing mounted on the,

turret and containing a set of intermeshing gears, -one of whichis fixedly associated with the tap while theother one loosely'suppo'rts for. sliding and rotary movement a countershaft, means'un'der control of the work for 1mp arting a rotary movement to' said'countershaft upon axial advance of thetu'rret beyond a predetermined'point in its path of axial i'eo movement, and'meansfdependent upon the axial movement oft'he turret beyond another predetermine'd'point in' its path forconnectingsaid "countersliaftfwith one of'the-- gears in said'casing for driving the tap.

In testimeay'where f I'aifixmysi mture at 10 S. La SalleSt-Q Chicago, Illinois,

' r OLAF'HEGSTAD.

two intermeshing gears of equal diameter in vertical alignment with each other, the lower gear being rotatable on said fixedstem and carrying in fixed relation and in alinement with said stem the tap, said last named gear having a clutch face, a key slidable on said stem and adapted to engage said clutch face for holding said gear positively againstrotation, means mountedon the gearcasing of theturret for releasing said key from holding engagement with said gear when the turret has been advanced to a predetermined point, and means constrained to exert a driving force upon said gear after release'of the holding key therefrom, said driving means for said gear being constrained to exert the driving force during the advance of the turrettowards the 'pointand being released fully to exert their driving force subsequent to the release of said key from said gear. V

iii-5 

